Signed-off-by: Jan Kara <jack@xxxxxxxx>
---
include/linux/fsnotify_backend.h | 50 ++++++++++++++++++++++++----------------
1 file changed, 30 insertions(+), 20 deletions(-)
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 65a517dd32f7..dd6ddb0287ed 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -195,40 +195,50 @@ struct fsnotify_group {
#define FSNOTIFY_EVENT_INODE 2
/*
- * a mark is simply an object attached to an in core inode which allows an
+ * A mark is simply an object attached to an in core inode which allows an
* fsnotify listener to indicate they are either no longer interested in events
* of a type matching mask or only interested in those events.
*
- * these are flushed when an inode is evicted from core and may be flushed
- * when the inode is modified (as seen by fsnotify_access). Some fsnotify users
- * (such as dnotify) will flush these when the open fd is closed and not at
- * inode eviction or modification.
+ * These are flushed when an inode is evicted from core and may be flushed
+ * when the inode is modified (as seen by fsnotify_access). Some fsnotify
+ * users (such as dnotify) will flush these when the open fd is closed and not
+ * at inode eviction or modification.
+ *
+ * Text in brackets is showing the lock(s) protecting modifications of a
+ * particular entry. obj_lock means either inode->i_lock or
+ * mnt->mnt_root->d_lock depending on the mark type.
*/
struct fsnotify_mark {
- __u32 mask; /* mask this mark is for */
- /* we hold ref for each i_list and g_list. also one ref for each 'thing'
+ /* Mask this mark is for [mark->lock, group->mark_mutex] */
+ __u32 mask;
+ /* We hold one for presence in g_list. Also one ref for each 'thing'
* in kernel that found and may be using this mark. */
- atomic_t refcnt; /* active things looking at this mark */
- struct fsnotify_group *group; /* group this mark is for */
- struct list_head g_list; /* list of marks by group->i_fsnotify_marks
- * Also reused for queueing mark into
- * destroy_list when it's waiting for
- * the end of SRCU period before it can
- * be freed */
- spinlock_t lock; /* protect group and inode */
- struct hlist_node obj_list; /* list of marks for inode / vfsmount */
- struct list_head free_list; /* tmp list used when freeing this mark */
- union {
+ atomic_t refcnt;
+ /* Group this mark is for. Set on mark creation, stable until last ref
+ * is dropped */
+ struct fsnotify_group *group;
+ /* List of marks by group->i_fsnotify_marks. Also reused for queueing
+ * mark into destroy_list when it's waiting for the end of SRCU period
+ * before it can be freed. [group->mark_mutex] */
+ struct list_head g_list;
+ /* Protects inode / mnt pointers, flags, masks */
+ spinlock_t lock;
+ /* List of marks for inode / vfsmount [obj_lock] */
+ struct hlist_node obj_list;
+ /* tmp list used when freeing this mark */
+ struct list_head free_list;
+ union { /* Object pointer [mark->lock, group->mark_mutex] */
struct inode *inode; /* inode this mark is associated with */
struct vfsmount *mnt; /* vfsmount this mark is associated with */
};
- __u32 ignored_mask; /* events types to ignore */
+ /* Events types to ignore [mark->lock, group->mark_mutex] */
+ __u32 ignored_mask;
#define FSNOTIFY_MARK_FLAG_INODE 0x01
#define FSNOTIFY_MARK_FLAG_VFSMOUNT 0x02
#define FSNOTIFY_MARK_FLAG_OBJECT_PINNED 0x04
#define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x08
#define FSNOTIFY_MARK_FLAG_ALIVE 0x10
- unsigned int flags; /* vfsmount or inode mark? */
+ unsigned int flags; /* flags [mark->lock] */
void (*free_mark)(struct fsnotify_mark *mark); /* called on final put+free */
};
--
2.1.4
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